IMPROVING ESTIMATES OF m sin i BY EXPANDING RV DATA SETS

Abstract

We develop new techniques for estimating the fractional uncertainty (F) in the projected planetary mass (msini) resulting from Keplerian fits to radial-velocity (RV) datasets of known Jupiter-class exoplanets. The techniques include (1) estimating the distribution of msini using projection, (2) detecting and mitigating chimeras, a source of systematic error, and (3) estimating the reduction in the uncertainty in msini if hypothetical observations were made in the future. We demonstrate the techniques on a representative set of RV exoplanets, known as the Gang of 27, which are candidates for detection and characterization by a future astrometric direct imaging (ADI) mission. We estimate the improvements (reductions) in F due to additional, hypothetical RV measurements (RVMs) obtained in the future. We encounter and address a source of systematic error, "chimeras," which can appear when multiple types of Keplerian solutions are compatible with a single dataset. We find that for n′ = 10 new, hypothetical RVMs obtained in the last planetary year before 2025, with the same accuracy as the current available RVMs, F is reduced by ~18%. From there, each plus-one increase in 2 log n′ − log q , where q is the factor by which RVM measurement uncertainty is reduced, further reduces F by factor 0.18.

Indenoisoquinoline Topoisomerase Inhibitors Strongly Bind and Stabilize the MYC Promoter G-Quadruplex and Downregulate MYC

“…The decrease in intensity in CD spectra of G4 upon ligand binding has been previously reported. 58 The negative control compound 17 showed no effect on the CD spectrum.…”

On the Eccentricity of Proxima b

“…It is not immediately clear to the author what characteristics of the RV data set cause the bi-variate density to clump into the three zones, A, B, and C. Future RV observations will clarify which of the three chimeras represents the true eccentricity of Proxima b. Brown (2016) shows how to estimate the improvement in the accuracy of orbital parameters to be expected from future RV observations. Our strategic, long-term goal is to elevate the orbital analyses of exoplanets to meet the challenges of the sometimes complex distributions of probability density when an RV data set offers only limited constraints on some parameters, as here for eccentricity.…”

“…We expect that more information-future RV measurements of Proxima-will cause one feature to thrive and grow, while the two others will fade and evaporate. Brown (2016) shows how to estimate the improvement in the accuracy of orbital parameters to be expected from future RV observations.…”

“…Chimeras arise when the data set does not adequately constrain the type of orbit that is involved. Brown (2004) studied the chimeras in HD 72659 b, and Brown (2016) found chimeras in 16 of 27 RV data sets of Jupiterclass planets that are otherwise suitable for characterization by direct imaging. In this paper, we find three chimeras in the RV data set for Proxima b.…”

“…In this paper, we use a technique called "Monte Carlo (MC) projection" (Brown 2004(Brown , 2016, to study the probability densities of the RV orbital parameters of Proxima b, particularly its orbital eccentricity (ε), for which A-E report an upper limit, ε < 0.35. We show that MC projection recovers the A-E estimates of the orbital elements-all except ε.…”